The invention is generally related to the field of intravenous (xe2x80x9cIVxe2x80x9d) infusion devices such as infusion pumps and the associated flexible IV tubing and flow stop devices, and more particularly, to devices used to prevent free flow in an IV tube when the infusion pump is disengaged from the IV tube.
It is a common practice to deliver fluids such as medications to a patient intravenously by means of a pumping device such as a xe2x80x9cfour fingerxe2x80x9d pump or a peristaltic pump. Such pumps are useful because they can deliver the medication in a highly controlled fashion, and because they do so without coming in contact with the medication. The fluid is moved through a flexible IV tube by pressing a pumping member against the outer surface of the tube sufficiently to force fluid downstream through the tube into the patient.
Both a four finger pump and a peristaltic pump operate by occluding the tube at all times so that there can be no free flow or uncontrolled flow between the fluid reservoir and the patient. In the case of a four finger pump, either an upstream valve finger or a downstream valve finger occludes the tube at all times. In the case of a peristaltic pump, at least one of the peristaltic fingers is at all times occluding the tube.
It is common for the pumping mechanism to be disposed in a housing with a hinged door. The tube through which the fluid is to be moved is placed in contact with the pumping mechanism inside the door, with the upstream and downstream ends of the tubing typically extending out the top and bottom, respectively, of the door opening. As the door is shut over the tube, a platen presses against the IV tube to provide a backing surface against which the pumping members can occlude the tube.
This arrangement of the IV tube relative to the pumping mechanism requires that there be some means for preventing flow in the tube when the door is open. Otherwise, during the process of mounting or removing the tube from the pumping mechanism, an unwanted flow of fluid could occur in the IV tube. This could result in the uncontrolled infusion of medication into the patient under the influence of the static head pressure in the tube. Known devices for preventing unwanted flow in the tube include manual clamps separate from the infusion pump, and automatic occluding devices mounted on the pump.
The manual clamp devices require some manipulation skill on the part of the attending technician, and there is the chance that the technician will forget to properly time the occlusion of the tube relative to the opening of the door on the pumping device. Furthermore, the door may be accidentally opened which could result in free flow in the tube.
The automatic flow stop engagement system disclosed in U.S. Pat. No. 5,453,098 has been a major advance in the art. However, in the case where the hinge or hinges of the door of the pump must be moved forward so that the pump has a narrow profile and can be placed closely beside another medical device without interfering with that device when the pump door is opened, such a door may not be squared with the tube. When the platen is mounted to the inner surface of the door, it may apply an undesirable rolling force to the tube when the door is opened and closed. Such a rolling force may stress the tubing any may move the tube out of the correct position in relation to the pumping mechanism and the automatic flow stop feature provided by the pumping mechanism may not be present because the tube is out of position. Typically, the action of opening the door is relied on to initiate the occlusion of the IV tube by the clamp and the action of closing the door is relied on to initiate the release of the IV tube from the clamp. Therefore, free flow of fluid could occur if the door is not located properly in relation to the tube. However, for purposes of ease in automatically controlling the clamp on the tube by the actions of the door opening and closing, it is desirable that door continue to effect such clamp control.
In designs where an engagement device such as a hooked arm is formed as part of the door and which engages the flow stop to move it to the occlusion position before the door permits disengagement of the pumping mechanism with the tube, it would be desirable to provide a warning to medical treatment personnel if the engagement mechanism is not in the correct position before the door is opened. A manual clamp could then be applied to the tube before the door of the pump is opened.
Therefore, those skilled in the art have recognized a need for an apparatus that will automatically and positively occlude an IV tube before the pumping mechanism is disengaged from the tube. A need has also been recognized for an apparatus that will automatically and positively maintain the IV tube in an occluded state until after the pumping mechanism is engaged with the tube and will then move the flow stop to a flow configuration. A need has also been recognized for an apparatus that will perform the above-discussed operations on the tube with a door that has been mounted in a more forward position to accommodate the placement of the pumping apparatus in close proximity to other medical devices. A further need has been recognized for a detection system that will determine if a flow stop engagement device is present with the pump door and will provide an alert if the engagement device is not detected. The present invention fulfills these needs and others.
The present invention is directed to avoiding the free flow of fluid through a medical instrument by judicious operation of a flow stop in conjunction with instrument loading and unloading operations. With more particularity, a platen is used to control a flow stop coupled to a tube so that movement of the door of the medical instrument controls the configuration of the flow stop.
In one aspect in accordance with the invention, an apparatus is provided for controlling a flow stop to reside in an occluding configuration at which the flow stop occludes a resilient tube and to reside in a flow configuration at which the flow stop permits flow through the resilient tube by the position of a door that is mounted with a first hinge to the housing of a medical instrument, the apparatus comprising a base on the flow stop for holding the resilient tube, a slide clamp slidably mounted on said base and engaging the tube, the slide clamp adapted for movement between the occluding configuration and the flow configuration, and a platen mounted in relation to the housing with a second hinge, the second hinge located at a position different from the position of the first hinge but such that the platen is disposed between the door and the slide clamp of the flow stop wherein moving the door towards the housing engages the platen causing it to engage the slide clamp to move the slide clamp to the flow configuration whereby fluid may flow through the tube.
In more detailed aspects, the platen comprises a body portion and a flow stop actuator portion disposed as an extension of and offset from the body portion of the platen such that the body portion of the platen engages the tube against the medical instrument while being pivoted into position by the movement of the door and the actuator portion contacts the flow stop before the slide clamp may be moved to the open position. Further, the flow stop comprises a locking arm engaged with the slide clamp that prevents the slide clamp from being moved to the flow configuration, and the flow stop comprises a release tab connected to the locking arm that disengages the locking arm from the slide clamp when the release tab is moved to a released position, wherein the flow stop actuator portion of the platen is disposed so as to contact the release tab of the flow stop and move it to the released position before the slide clamp is moved to the flow configuration.
The medical instrument also includes datum pins located at selected positions on the instrument, the pins having a predetermined length selected so that when the platen is engaged with the pins, the platen will have a known location in relation to the medical instrument and wherein the length of the datum pins is selected so that the flow stop actuator portion of the platen will contact the release tab of the flow stop, in other aspects. Further, the second hinge of the platen comprises a floating hinge adapted to permit the platen to be located in contact with all the datum pins when the door engages the platen. Additionally, the platen comprises a plurality of contact datum surfaces disposed on the platen at positions selected to engage the datum pins when the door positions the platen in contact with the datum pins. In further aspects, the platen comprises a load distribution rib located on the platen so as to receive the force or load of the door and distribute that force along the platen. Additionally, the door comprises a pressure surface located on the inside of the door at a location so as to contact the load distribution rib of the platen to press the platen against the datum pins.
In yet further aspects, the housing of the medical instrument comprises an anchor yoke that is biased toward the housing, the door comprises a pivotally mounted handle located to engage and capture the anchor yoke to firmly hold the door in a closed position against the housing, and wherein the anchor yoke is biased towards the housing by an extent that will assure that the door contacts the load distribution rib of the platen thereby forcing the platen into contact with the datum pins. In more detailed aspects, the handle includes a sear with a hook, the sear and hook located so as to engage the slide clamp of the flow stop when the door is in the closed position and to move the slide clamp to the occluding configuration when the door of the medical instrument is opened thereby preventing free flow through the tube.
In yet further more detailed aspects, the apparatus comprises a sear detector located in the medical instrument at a position selected so as to detect the presence of the sear in position in relation to the slide clamp, the detector providing a sear detection signal and a processor connected to the sear detector to receive the sear detection signal and adapted to provide a sear alert signal in the event that the sear is not detected by the sear detector. Further, the sear detector comprises a photo emitter and photo receiver both directed towards a predetermined location for a sear and the sear comprises a photo-reflective surface. The apparatus further comprises a flow stop detector located in the medical instrument at a position selected so as to detect the presence of the flow stop in the medical instrument and configured to provide a flow stop detection signal and a processor connected to the flow stop detector to receive the flow stop detection signal and adapted to provide a flow stop alert signal in the event that the flow stop is not detected by the flow stop detector.
In other detailed aspects, the first hinge is located forward on the housing so that the door is separated from the flow stop when the flow stop is mounted in the medical instrument.
In another main aspect, an apparatus is provided for controlling the flow of fluid through a tube mounted in a medical instrument, the medical instrument including a flow mechanism that engages the tube to precisely regulate the flow of fluid through the tube to a patient, and a flow stop mounted to the medical instrument, the flow stop having an occluding configuration at which the flow stop occludes the tube and a flow configuration at which the flow stop permits flow through the tube, the medical instrument having a housing to which a door is mounted with a first hinge, the apparatus comprising a base on the flow stop for holding the tube, a slide clamp slidably mounted on said base and engaging the tube, the slide clamp adapted for movement between the occluding configuration and the flow configuration, and a platen mounted in relation to the housing with a second hinge, the second hinge located at a position different from the position of the first hinge but such that the platen is disposed between the door and the flow mechanism and the flow stop such that when the door is moved towards the flow mechanism, the door engages the platen causing it to engage the tube against the flow mechanism to occlude the tube by the flow mechanism and then engages the slide clamp of the flow stop to move the slide clamp to the flow configuration thereby avoiding a free flow condition.
In another main aspect, an apparatus is provided for controlling the flow of fluid through a tube mounted in a medical fluid infusion pump, the pump including a pumping mechanism that engages the tube to precisely pump the fluid through the tube to a patient, the tube having a flow stop having a base and a slide clamp slidably mounted on the base and engaging the tube, the slide clamp having an occluding configuration at which the slide clamp occludes the tube and a flow configuration at which the slide clamp permits flow through the tube, the pump having a housing to which a door is mounted with a first hinge, the apparatus comprising a platen mounted in relation to the housing with a second hinge, the second hinge located at a position different from the position of the first hinge but such that the platen is disposed between the door and the pumping mechanism and the flow stop such that when the door is moved towards the pumping mechanism, the door engages the platen causing it to engage the tube against the pumping mechanism to occlude the tube by the pumping mechanism and then engages the slide clamp of the flow stop to move the slide clamp to the flow configuration thereby avoiding a free flow condition.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, principles of the invention.